Excitonic pattern formation from a wrinkling instability in a van der Waals heterostructure

Abstract

We studied photoluminescence of spatially indirect excitons (IXs) in a MoSe${}_2$/WSe${}_2$ van der Waals heterostructure. We observed a quasi-periodic triangular pattern of IXs with a characteristic spatial wavelength $\sim 2.6\hat{I}¼\mathrm{m}$. Our theoretical analysis using a Föppl-von Kármán theory finds an elastic instability that produces triangular patterns with micrometer-scale wavelengths. This mechanism is consistent with the wavelength, symmetry, excitation power dependence, and temperature dependence of the observed IX pattern.